Add PEP 761 to What's New (python#126550)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: sethmlarson

Doc/whatsnew/3.14.rst

@@ -791,6 +791,16 @@ Changes in the Python API
 Build changes
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+PEP 761: Discontinuation of PGP signatures
+------------------------------------------
+
+PGP signatures will not be available for CPython 3.14 and onwards.
+Users verifying artifacts must use `Sigstore verification materials`_ for
+verifying CPython artifacts. This change in release process is specified
+in :pep:`761`.
+
+.. _Sigstore verification materials: https://www.python.org/downloads/metadata/sigstore/
+
 
 C API changes
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